Outline

Objective: Recent studies have shown that cyclooxygenase-2 (COX-2) plays an important role in tumor growth and tumor neovascularization. A growing body of literature supports the use of COX-2 inhibitors in treatment of various cancers. Up until now no data concerning potential COX-2 expression are available for intracranial schwannomas. The aim of this study is to analyze the pattern of COX-2 expression in sporadic vestibular schwannomas (sporadic VS) and neurofibromatosis type 2 associated vestibular schwannomas (NF2 associated VS).

Methods: Using immunohistochemistry, we investigated the expression of COX-2 in NF2 associated VS and in sporadic VS. Fifteen paraffin-embedded specimens of each NF2 associated VS and sporadic VS were evaluated. An immunohistochemical score was used to interpret the extent and intensity of COX-2 staining. Tumor proliferation was analyzed using Ki-67 immunohistochemistry. More than 1000 cells per tumor were evaluated by light microscopy on high-field power by a blinded observer. In addition, microvascular density was analyzed using von-Willebrand-factor.

Results: Expression of COX-2 was detected in 29 specimens (96.7%). The intensity and extension of the staining was heterogeneous: 11 tumors (36.7%) were graded as weakly, 9 (30%) as moderately, and 9 (30%) as strongly COX-2 positive, without difference between sporadic and NF2 associated VS. One specimen (3.3%) was COX-2 negative. Proliferation of sporadic VS was significantly higher than of NF2 associated VS (p<0,001). No statistically significant difference was found between the microvascular densities of both groups.

Conclusions: Our data demonstrate that COX-2 is expressed in the majority of VS with heterogeneous intensity. This suggests that the COX-2 pathway is involved in the pathophysiology of VS, and that COX-2 might become a therapeutic target in the treatment of VS.